1. Field
Embodiments relate to an electrolyte for a lithium secondary battery and a lithium secondary battery including the same.
2. Description of the Related Art
An electrolyte for a lithium secondary battery is formed from a mixed solution prepared by dissolving one or more lithium salt selected from LiPF6, LiBF4, LiBOB, LiFOB, LiTFSI, LiBETI and others into a solvent mixture of cyclic esters such as ethylene carbonate (EC), propylene carbonate (PC), butylenes carbonate (BC), gamma-butyrolactone (GBL), gamma-valerolactone (GVL) and others, and chain esters such as dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), acetate, propionate, butyrate, hexanoate and others. However, the above-mentioned organic solvents as combustible materials have limitations in that they are liable to cause combustion, and they are vulnerable to safety. Therefore, a way of enhancing flame retardancy by additionally mixing flame retarding additives of fluorine-based compounds or phosphorus compounds such as phosphate, phosphazene and others with the electrolyte for lithium secondary battery has been examined.
However, the electrolyte for a lithium secondary battery has a limitation that, when the flame retarding additives are added in the electrolyte for a lithium secondary battery, a solid electrolyte interface (SEI) having high resistance is formed on the surface of the negative electrode to result in a drop in performance of the lithium secondary battery.